S: We have no interview this week, so I want to do a quick Name That Logical Fallacy. This one actually comes from Mike Lacelle, who wrote to me recently.

Steve, I have a question. If I'm talking to someone about Jenny McCarthy being the celebrity poster child for the antivaccination movement and happen to mention that she was once a Playboy Playmate of the Year, would that be an example of poisoning the well? What if I mention that she used to, among other things, eat her boogers on MTV? Is there a difference between the two (logically, not physically)? Hell, now that I think about it, is poisoning the well even considered a logical fallacy? Mike.

S: Well, I actually blogged about this last week, too. This is a good one.

B: It's an ad hominem.

S: Yeah, this comes up a lot. You know, poisoning the well is a logical fallacy, and, as Bob just said, it is actually a form of an ad hominem. It's slightly different. It has the same form of an ad hominem logical fallacy in that it attempts to say, "This person is wrong—their argument is wrong—because they have some negative attribute, or some negative association or affiliation." A ad hominem logical fallacy is more direct. "This guy's wrong because he's close-minded." Right? That's the one that skeptics are actually typically the target of.

B: Right.

S: Or, it's also like saying, "This guy's wrong because he's crazy." Or, "This guy's wrong because he's a liar and you can't trust him." Those are ad hominem arguments, and they're a logical fallacy because somebody could be a liar, or close-minded, or whatever, and still be right. It doesn't mean – it doesn't say anything about the argument itself. Poisoning the well is more indirect. You're not necessarily saying something directly negative about that person, but you're trying to bias your audience, or whoever you're talking to, against the argument by giving it some kind of negative attribute or association. One of the most common examples of this is trying to pin anything that you're arguing against on Adolf Hitler. If you recall the movie "Expelled", that's basically what they were trying to do to evolution. You know, "Hitler believed in evolution, you know, so you can't trust anyone – those evolutionists", which is, you know, it's a logical fallacy because it says absolutely nothing about the scientific evidence for or against evolution as a theory. We also run into this a lot because, certainly, on the show, we do bring up attributes of people that hold unskeptical viewpoints, and that's not necessarily a logical fallacy. It's not a logical fallacy just simply to call someone a name. It's also not a logical fallacy to say, "This person is"—you know, whatever—"this person is nuts, and here's why", and then describe all the ways in which their arguments are wrong and their thinking goes awry. That's OK, too. It's a logical fallacy only when it takes the form, "This person's wrong because of the personal attribute that they have." So, thanks, Mike, for that question.

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